JPS61143916A - Vacuum valve for breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vacuum valve for a circuit breaker, the container of which comprises at least one metal part and an insulating material part axially connected to the metal part.

[Prior Art] A vacuum valve for a circuit breaker, the container of which has at least one metal part and an insulating material part axially connected to the metal part, the insulating material part evacuating the mutual insulation of front contacts. This is guaranteed inside the valve but not on the outer wall, and the insulating material part and the metal part are covered at least partially in the axial direction of these parts by a shrink tube, which It is known from GB 2,029,843 that guarantees the required minimum value of the creepage distance for discharge between the applied parts. In this known vacuum valve, the shrink tube and the container are connected in order to prevent corona discharges from occurring between the shrink tube and the container, which can occur in air bubbles on the insulating parts of the container, which usually consist of ceramic. A layer of grease is placed in between.

This grease layer must be applied very carefully,
This is because even small air bubbles between the shrink tube and the container underneath can cause corona discharges or even spark discharges, and these discharges can damage the adjacent insulation and therefore the vacuum valve during operation of the vacuum circuit breaker. There is a risk of destroying the whole thing. Ensuring that the grease layer and shrink tubing are installed without bubbles is relatively labor intensive.

A vacuum valve is known from European Patent No. 0077518, in which a rubber tape impregnated with silicone oil is adhered to the outer wall of the container. This rubber tape partially covers the insulated container part and ensures that a film of silicone oil forms on the insulation.

This prevents the formation of a moisture film and suppresses leakage current. The rubber tape then serves as a reservoir for the silicone oil.

However, this conventional example is not suitable for increasing the spark gap of a vacuum valve, the porous rubber tape only adheres to the container wall with relatively little pressure, and the silicone oil release into the surroundings. Due to the function of the rubber tape as a reservoir, air bubbles inevitably form in the insulation, and when the spark gap is not guaranteed by the insulating material part of the container, a discharge occurs in this air bubble and the surrounding There is a risk of damaging the insulation.

[Problems to be Solved by JA Ming] The present invention provides a particularly simple and versatile method for suppressing leakage current and increasing the spark gap of the container in the above-mentioned type of vacuum valve. The purpose is to

[Means for solving the problem] This object is based on the invention, in which the shrink tube has an inner surface consisting of an adhesive layer or a plastic sealing putty, and the area covered by the shrink tube of the insulating material part. This is achieved by being sealed from the surrounding atmosphere in a moisture-tight manner and having sufficient resistance to dielectric breakdown.

Effects of the Invention The shrink tube according to the invention ensures a moisture-tight bond to the insulating material parts. The shrink tubing fits snugly to the insulating material to avoid creating air bubbles that could create electrical discharges. Breakdown of the surrounding insulation, which could occur due to electrical discharges in the bubbles, is avoided by the shrink tube when it is sealed and shrunk in a moisture-tight manner. This means that the shrink tube slowly fills the pores during contraction,
This is thought to be due to the fact that air that happens to be present at that time is removed without forming bubbles.

If at the same time rust protection is to be achieved for the metal parts, it is advantageous that the shrink tube also closes off the metal parts from the surrounding atmosphere in a moisture-tight manner and is made of a rust-proofing material.

For a moisture-tight closure, it is sufficient for the shrink tube to have a moisture-tight seal on the metal part or the insulating material part only in the region of its ends. The container comprises two cylindrical insulating material sections and a metal section disposed between them, the shrink tubing completely covering the metal sections and at least partially covering the refill material section, and the shrink tubing completely covering the metal sections and at least partially covering the refilling material section, A significant reduction in the assembly length of the vacuum valve container is obtained when the vacuum valve is separated in a moisture-tight manner from the vacuum valve. The total length of the metal part is thereby also utilized as creepage distance. In particular in construction types with a central isolation chamber, the creepage distance can be increased significantly, ie by the sum of the length of the isolation chamber and the difference of the radius of the isolation chamber with respect to the radius of the insulating material section. If the shrink tube in this case not only covers the insulating material parts but also the metal parts in a moisture-tight manner and has a dielectric strength corresponding to the test voltage, the spark gap of the vacuum valve is increased accordingly.

When the shrink tube fits only on the cylindrical cross section, the cross section of the vacuum valve may differ from the usual circular shape.

A metal part is adjacent on both sides of the insulating material part, the insulating material layer overlaps both metal parts, the overlap with only one metal part creates the required minimum distance, and the insulating material layer has a value of half the maximum test voltage. A relatively thin layer of insulating material whose dielectric strength is below the maximum test voltage of the vacuum valve is sufficient when it has a dielectric strength exceeding the maximum test voltage of the vacuum valve. In this case a dielectric strength of half the maximum test voltage is sufficient. This is because the floodover has to run through the layer of insulating material twice.

When commercially available shrink tubes do not have the necessary voltage strength, two or more shrink tubes can be stacked together.

[Embodiments] Next, the present invention will be described in detail with reference to drawings showing three embodiments of the vacuum valve based on the present invention.

In the embodiment shown in FIG. 1, the container of the vacuum valve has an insulating material part l formed as a truncated cone and a metal part 2 axially connected to the insulating material part l. Shrink tube 3 to increase the voltage strength of this vacuum valve
is provided, the shrink tube having on its inner surface a moisture-tight closed layer 4, which can be a layer of adhesive or a layer of sealing putty. The shrink tube 3 overlies the ring-shaped area 13 of the insulating material part 1 . The shrink tube also prevents a fluffover in the air even at the maximum permissible voltage load of the vacuum valve and thus increases the spark gap. The shrink tube 3 has a dielectric strength corresponding to the highest permissible voltage. This ensures that no flooding from the metal part 2 to the metal part 5 of the opposite polarity can occur between the shrink tube 3 and the insulating material part 1 as well as through the shrink tube 3. The creepage path for the discharge therefore extends not only through the insulating material part l, but also through the shrink tube 3 and into the metal part 2.

In this case, only the edge area is connected to the insulating material part l in a moisture-tight manner, and if a floating overflow in the air is avoided by the size of the insulating material part l, i.e. a spark gap is already guaranteed by the insulating material part 1. If the shrink tube 3 does not need to be in close contact with the metal part 2 over its entire axial extent, the moisture-impermeable layer 4 of the shrink tube 2 may additionally have anti-rust properties. It is advantageous to do so, so that special anticorrosion measures of the metal part 2 are not required in the covered area.

In the embodiment shown in FIG. 2, the shrink tube 3 connects two different insulating material parts 6 and 7 of the container of the vacuum valve, the insulating material parts 6, 7 being ceramic tubes with a corrugated surface. is advantageous. Insulating material parts 6 and 7
In between is provided a metal part 8 which forms the actual isolation chamber. The shrink tube 3 adheres in a moisture-tight manner to the two edge material parts 6 and 7, but floats over the sharp corner 9 of the metal part 8 at the transition to the actual isolation chamber;
Therefore, a hollow chamber is formed between the metal part and the metal part. In this embodiment, the creepage path for the discharge is provided by both edge material sections 6 and 7.
and extends through the surface of the shrink tube 3. Thereby, the creepage path is the length of the isolation chamber and the insulating material portion of the radius of the isolation chamber 6.
It is extended by the sum of the difference for the radius of 7. This allows a significant miniaturization of such vacuum valves.

In the embodiment shown in FIG. 3, the shrink tube 3 surrounds a cylindrical part of insulating material lO, to which on each side one metal part 11 or 12 is connected. The shrink tube 3 overlaps the metal material parts 11 and 12 to the extent that the overlap with one of the metal parts 11, 12 guarantees a minimum distance for the suppression of leakage currents and over the metal part and the insulating material part. The entire surface is tightly sealed to prevent moisture from passing through. This embodiment shows that the discharge passing through the shrink tube passes through the shrink tube twice, i.e. both metal parts 11 and 1.
2, which has to be penetrated once each, allows particularly advantageous dimensions of the shrink tube 3 and increases the spark gap by the overlap area on one of the metal parts 11 or 12. In this embodiment, therefore, a shrink tube can be used whose breakdown voltage is only slightly more than half the maximum permissible voltage of the vacuum valve. If only the creepage path is to be increased, it is sufficient in this embodiment for the insulating material part 10 to be protected from moisture ingress by a shrink tube. In this case, if the shrink tube is tightly sealed only on the two metal parts 11 and 12 in a moisture-tight manner, the shrink tube is tightly sealed on the insulating material part 10 itself in a moisture-tight manner. The insulating material portion 10 therefore does not have to be in such a recess that the shrink tube adhesive or sealing putty can penetrate completely and with a moisture-tight closure, for example relatively. It can be made of coarse-grained ceramic.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of one embodiment of a vacuum valve according to the present invention, and FIGS. 2 and 3 are partially cutaway side views of different embodiments. 1.6, 7, 10 fist...Insulating material part, 2゜8.1
1, 12... Φ metal part, 3... Shrink tube.

Claims (1)

[Scope of Claims] 1) A vacuum valve for a circuit breaker, the container comprising at least one metal part and an insulating material part axially connected to the metal part, wherein the insulating material part is connected to the mutual contact between the two contacts. To ensure insulation inside the vacuum valve but not on the outer wall, the insulating material part and the metal part are covered over at least part of the axial direction of these parts by a shrink tube, which In order to guarantee the required minimum creepage distance for electrical discharge between the energized parts of the bulb, the shrink tube has an inner surface consisting of an adhesive layer or a flexible sealing putty, and the shrink tube of the insulating material part A vacuum valve for a circuit breaker, characterized in that a covered area is closed from the surrounding atmosphere to prevent moisture from passing through, and has sufficient resistance against dielectric breakdown. 2) A vacuum valve according to claim 1, characterized in that the shrink tube closes the metal part in a moisture-tight manner and is made of anti-corrosion material. 3) The container comprises two cylindrical insulating material parts and a metal part placed between them, the shrink tube completely covers the metal parts and at least partially covers both insulating material parts, and the shrink tube covers the surrounding parts. The vacuum valve according to claim 1 or 2, characterized in that the vacuum valve is separated from the atmosphere so as not to allow moisture to pass therethrough. 4) The insulating material part is flanked by metal parts on both sides, and the shrink tube overlaps both metal parts and is impermeable to moisture, such that the overlap with one of the metal parts guarantees a minimum value for the suppression of leakage current. 2. Vacuum valve according to claim 1, characterized in that the layer of insulating material has a dielectric strength greater than half the value of the maximum test voltage but less than the maximum test voltage. 5) The shrink tube fits tightly against the insulating material part of the container in a moisture-tight manner, forming a hollow chamber over a limited range in the axial direction in the area of the metal part, and extending beyond the insulated container part to form a hollow chamber. 2. Vacuum valve according to claim 1, characterized in that the insulation path extending to the beginning of the chamber is larger than the permissible spark gap.